Admidio from 5.0.0 before 5.0.16 contains an insecure direct object reference vulnerability in ForumService::saveTopic() that allows authenticated… (CVE-2026-111912)

The vulnerability in Admidio affects versions starting from 5.0.0 before 5.0.16. It is an insecure direct object reference (CWE-639) in the ForumService::saveTopic() method. Authenticated members can exploit this by substituting the topic_uuid parameter in their own topic_save request, reusing their CSRF token, to overwrite another user's forum topic title and first post. This results in unauthorized modification of forum content without requiring additional user interaction.

The vulnerability allows authenticated users to modify other users' forum topics, specifically the topic title and the first post content. This can lead to integrity issues within the forum, potentially misleading users or disrupting discussions. There is no indication of confidentiality or availability impact. The CVSS score is 6.5 (high severity) with vector AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N, indicating network attack vector, low attack complexity, requiring privileges, no user interaction, unchanged scope, no confidentiality impact, high integrity impact, and no availability impact.

A fix is available in Admidio version 5.0.16. Users should upgrade to version 5.0.16 or later to remediate this vulnerability. Until upgrading, restrict forum access to trusted users only and monitor for unauthorized topic modifications. Patch status is confirmed by the version range indicating the fix in 5.0.16.